[mlir][vector] Add folder for no-op InsertStridedSliceOp

mlir/include/mlir/Dialect/Vector/VectorOps.td

let extraClassDeclaration = [{
     static StringRef getStridesAttrName() { return "strides"; }
     VectorType getSourceVectorType() {
       return source().getType().cast<VectorType>();
     }
     VectorType getDestVectorType() {
       return dest().getType().cast<VectorType>();
     }
   }];
+
+  let hasFolder = 1;
 }
 
 def Vector_OuterProductOp :
   Vector_Op<"outerproduct", [NoSideEffect,
     PredOpTrait<"lhs operand and result have same element type",
                 TCresVTEtIsSameAsOpBase<0, 0>>,
     PredOpTrait<"rhs operand and result have same element type",
                 TCresVTEtIsSameAsOpBase<0, 1>>]>,

mlir/lib/Dialect/Vector/VectorOps.cpp

if (failed(
           makeI64ArrayAttr(sourceShapeAsDestShape, op.getContext()), destShape,
           offName, "source vector shape",
           /*halfOpen=*/false, /*min=*/1)))
     return failure();
 
   return success();
 }
 
+OpFoldResult InsertStridedSliceOp::fold(ArrayRef<Attribute> operands) {
+  if (getSourceVectorType() == getDestVectorType())
+    return source();
+  return {};
+}
+
 //===----------------------------------------------------------------------===//
 // OuterProductOp
 //===----------------------------------------------------------------------===//
 
 /// Build an op without mask, use the type of `acc` as the return type.
 void OuterProductOp::build(OpBuilder &builder, OperationState &result,
                            Value lhs, Value rhs, Value acc) {
   result.addOperands({lhs, rhs, acc});

mlir/test/Dialect/Vector/canonicalize.mlir

 // CHECK-LABEL: func @vector_multi_reduction_single_parallel(
 //  CHECK-SAME:     %[[v:.*]]: vector<2xf32>
 func @vector_multi_reduction_single_parallel(%arg0: vector<2xf32>) -> vector<2xf32> {
     %0 = vector.multi_reduction #vector.kind<mul>, %arg0 [] : vector<2xf32> to vector<2xf32>
 
 //       CHECK:     return %[[v]] : vector<2xf32>
     return %0 : vector<2xf32>
 }
+
+// -----
+
+// CHECK-LABEL: func @insert_strided_slice_full_range
+//  CHECK-SAME: %[[SOURCE:.+]]: vector<16x16xf16>, %{{.+}}: vector<16x16xf16>
+func @insert_strided_slice_full_range(%source: vector<16x16xf16>, %dest: vector<16x16xf16>) -> vector<16x16xf16> {
+  %0 = vector.insert_strided_slice %source, %dest {offsets = [0, 0], strides = [1, 1]} : vector<16x16xf16> into vector<16x16xf16>
+  // CHECK: return %[[SOURCE]]
+  return %0: vector<16x16xf16>
+}

mlir/test/Dialect/Vector/vector-transforms.mlir

func @cast_away_insert_strided_slice_leading_one_dims(%arg0: vector<1x8xf16>, %arg1: vector<1x8x8xf16>) -> vector<1x8x8xf16> {
   // CHECK: %[[INSERT:.+]] = vector.insert_strided_slice %[[SRC]], %[[DST]] {offsets = [0, 0], strides = [1]} : vector<8xf16> into vector<8x8xf16>
   %0 = vector.insert_strided_slice %arg0, %arg1 {offsets = [0, 0, 0], strides = [1, 1]} : vector<1x8xf16> into vector<1x8x8xf16>
   // CHECK:    %[[RET:.+]] = vector.shape_cast %[[INSERT]] : vector<8x8xf16> to vector<1x8x8xf16>
   // CHECK: return %[[RET]]
   return %0: vector<1x8x8xf16>
 }
 
 // CHECK-LABEL: func @cast_away_insert_strided_slice_leading_one_dims_one_element
+//  CHECK-SAME: %[[ARG0:.+]]: vector<1x1xf16>, %{{.+}}: vector<1x1x1xf16>
 func @cast_away_insert_strided_slice_leading_one_dims_one_element(%arg0: vector<1x1xf16>, %arg1: vector<1x1x1xf16>) -> vector<1x1x1xf16> {
-  // CHECK: vector.shape_cast %{{.+}} : vector<1x1xf16> to vector<1xf16>
-  // CHECK: vector.shape_cast %{{.+}} : vector<1x1x1xf16> to vector<1xf16>
+  // CHECK: %[[CAST:.+]] = vector.shape_cast %[[ARG0]] : vector<1x1xf16> to vector<1x1x1xf16>
   %0 = vector.insert_strided_slice %arg0, %arg1 {offsets = [0, 0, 0], strides = [1, 1]} : vector<1x1xf16> into vector<1x1x1xf16>
+  // CHECK: return %[[CAST]]
   return %0: vector<1x1x1xf16>
 }
 
 // CHECK-LABEL: func @cast_away_transfer_read_leading_one_dims
 func @cast_away_transfer_read_leading_one_dims(%arg0: memref<1x4x8x16xf16>) -> vector<1x4xf16> {
   // CHECK: %[[C0:.+]] = constant 0 : index
   %c0 = constant 0 : index
   // CHECK: %[[F0:.+]] = constant 0.000000e+00 : f16